Introduction
Mild cognitive impairment (MCI) is an intermediate stage of cognitive impairment between changes seen in normal cognitive aging and those related to dementia, and is considered a goal to prevent the progression of Alzheimer’s disease [1]. MCI is characterized by objective cognitive decline in one or more cognitive domains [2, 3]. MCI patients with depression are at more risk of dementia than the patients without depression [4]. Reducing depression may help prevent or delay further cognitive decline [5]. Cognitive rehabilitation can prevent cognitive decline in people with MCI through neuroplasticity [6]. Considering the increase in the elderly population and the possibility of MCI and depression in the elderly, improving their cognitive status and reducing their depression are necessary to prevent Alzheimer’s disease and increase their quality of life. The present study aims to determine the effect of cognitive rehabilitation on the cognitive status and depression of older men with MCI.
Methods
This is a quasi-experimental study with a pre-test/post-test design using a control group. The study population consists of all older men over 60 years of age with MCI living in Amir Al-Momenin nursing home in Kerman, Iran in 2021. With a purposeful sampling method and based on the inclusion criteria, 24 older men were selected as the study samples. They were randomly assigned to the intervention (n=12) and control (n=12) groups by random drawn method. The inclusion criteria were consent to participate in the study, age≥ 60 years old, diagnosis of MCI (score 21-24 in the Mini-Mental State Examination), diagnosis of depression (score at least 5 in the geriatric depression scale), having at least a reading and writing literacy, and no other neurological disorders (Alzheimer’s disease, Parkinson’s disease and multiple sclerosis) according to physician attending nursing homes. The exclusion criteria were the return of questionnaires incomplete and unwillingness to continue participation.
The Mini–Mental State Examination was used to assess cognitive status and the geriatric depression scale was used to measure the depression of participants before and after rehabilitation. The intervention group received cognitive rehabilitation at 12 sessions, three sessions per week, each for 1 hour. The control group did not receive any intervention. The collected data were analyzed using descriptive statistics (No., Mean±SD) and inferential statistics (analysis of covariance) in SPSS software , version 19. The significance level was set at 0.05.
Results
The mean age of the participants was 62.08±2.39 years in the intervention group and 63.25±2.66 in the control group. In the intervention group, 75% (n=9) had lower than high school education and 25% (n=3) had a high school diploma. In the control group, 66.7% (n=8) had lower than high school education and 33.3% (n=4) had a high school diploma. After checking and verifying the assumptions of analysis of covariance (normality of data distribution, homogeneity of variance-covariance matrices, homogeneity of variance of two groups in the post-test stage, and homogeneity of the regression slopes), analysis of covariance was carried out. Wilks’ lambda, Pillai’s trace, Hotelling’s trace, and Roy’s largest root test statistics were significant (F=12.902, P=0.05). The eta squared value showed that 60% of the changes in the dependent variables were due to the effect of the independent variable (cognitive rehabilitation program). The significance level obtained from all the tests (P=0.001) indicated a significant difference between the two groups in at least one of the dependent variables. The results of the analysis of covariance showed that the mean score of the cognitive status after controlling the effect of the pre-test score in the two groups had a significant difference (P<0.05). As a result, the effect of cognitive rehabilitation on improving the cognitive status of the elderly with MCI was confirmed. Eta squared value showed that 41% of the changes in cognitive status score was due to the cognitive rehabilitation program. Moreover, the results showed that the mean score of depression after controlling the effect of the pre-test score in the two groups had a significant difference (P<0.05). As a result, the effect of cognitive rehabilitation on the depression of the elderly with MCI was confirmed. Eta squared value showed that 35% of the changes in depression score was due to the cognitive rehabilitation program.
Discussion
Providing cognitive rehabilitation exercises that include various programs of cognitive rehabilitation and emotional adjustment in real life is effective in improving the cognitive status and reducing depression of the elderly with MCI. The cognitive rehabilitation program can be effective in preventing the progression of MCI to dementia by improving cognitive functions and reducing depression of the elderly with MCI. It can be used to improve the mental health and quality of life of the elderly in medical centers and nursing homes. It is recommended that health professionals and nursing home managers include cognitive rehabilitation programs in their non-pharmacological treatment programs for the elderly. It is also recommended to establish supportive and rehabilitation centers throughout the country to screen and implement cognitive rehabilitation programs for the elderly to prevent the progression of MCI to Alzheimer’s disease.

Ethical Considerations
Compliance with ethical guidelines
This study obtained an ethical approval from the ethics committee of University of Sistan and Baluchestan (Code: IR.USB.REC.1400.003).

Funding
This study was extracted from a master thesis. It was not funded by any organizations.

Authors' contributions
The authors had equal contribution to the preparation of this article.

Conflicts of interest
The authors declare no conflict of interest.

Acknowledgements
The authors would like to thank all seniors participated in this study for their cooperations.

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